[PATCH 5/5] Documentation: ABI: document /sys/devices/system/cpu/

[Alex Chiang <achiang@hp.com>]

This interface has been around for a long time, but hasn't been
officially documented.

Since I wanted to extend the ABI, I figured I would document what
already existed.

Cc: Greg KH <greg@kroah.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Alex Chiang <achiang@hp.com>
---

 Documentation/ABI/testing/sysfs-devices-cpu |   42 +++++++++++++++++++++++++++
 1 files changed, 42 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-devices-cpu

diff --git a/Documentation/ABI/testing/sysfs-devices-cpu b/Documentation/ABI/testing/sysfs-devices-cpu
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+What:		/sys/devices/system/cpu/
+Date:		October 2009
+Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
+Description:
+		A collection of CPU attributes, including cache information,
+		topology, and frequency. It also contains a mechanism to
+		logically hotplug CPUs.
+
+		The actual attributes present are architecture and
+		configuration dependent.
+
+
+What:		/sys/devices/system/cpu/$cpu/online
+Date:		January 2006
+Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
+Description:
+		When CONFIG_HOTPLUG_CPU is enabled, allows the user to
+		discover and change the online state of a CPU. To discover
+		the state:
+
+		cat /sys/devices/system/cpu/$cpu/online
+
+		A value of 0 indicates the CPU is offline. A value of 1
+		indicates it is online. To change the state, echo the
+		desired new state into the file:
+
+		echo [0|1] > /sys/devices/system/cpu/$cpu/online
+
+		For more information, please read Documentation/cpu-hotplug.txt
+
+
+What:		/sys/devices/system/cpu/$cpu/node
+Date:		October 2009
+Contact:	Linux memory management mailing list <linux-mm@kvack.org>
+Description:
+		When CONFIG_NUMA is enabled, a symbolic link that points
+		to the corresponding NUMA node directory.
+
+		For example, the following symlink is created for cpu42
+		in NUMA node 2:
+
+		/sys/devices/system/cpu/cpu42/node2 -> ../../node/node2